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    <h1 align="center">Running a High-Performance Web Server for
    HPUX</h1>
<pre>
Date: Wed, 05 Nov 1997 16:59:34 -0800
From: Rick Jones &lt;<a
href="mailto:raj@cup.hp.com">raj@cup.hp.com</a>&gt;
Reply-To: raj@cup.hp.com
Organization: Network Performance
Subject: HP-UX tuning tips
</pre>
    Here are some tuning tips for HP-UX to add to the tuning page. 

    <p>For HP-UX 9.X: Upgrade to 10.20<br />
     For HP-UX 10.[00|01|10]: Upgrade to 10.20</p>

    <p>For HP-UX 10.20:</p>

    <p>Install the latest cumulative ARPA Transport Patch. This
    will allow you to configure the size of the TCP connection
    lookup hash table. The default is 256 buckets and must be set
    to a power of two. This is accomplished with adb against the
    *disc* image of the kernel. The variable name is tcp_hash_size.
    Notice that it's critically important that you use "W" to write
    a 32 bit quantity, not "w" to write a 16 bit value when
    patching the disc image because the tcp_hash_size variable is a
    32 bit quantity.</p>

    <p>How to pick the value? Examine the output of <a
    href="ftp://ftp.cup.hp.com/dist/networking/tools/connhist">ftp://ftp.cup.hp.com/dist/networking/tools/connhist</a>
    and see how many total TCP connections exist on the system. You
    probably want that number divided by the hash table size to be
    reasonably small, say less than 10. Folks can look at HP's
    SPECweb96 disclosures for some common settings. These can be
    found at <a
    href="http://www.specbench.org/">http://www.specbench.org/</a>.
    If an HP-UX system was performing at 1000 SPECweb96 connections
    per second, the TIME_WAIT time of 60 seconds would mean 60,000
    TCP "connections" being tracked.</p>

    <p>Folks can check their listen queue depths with <a
    href="ftp://ftp.cup.hp.com/dist/networking/misc/listenq">ftp://ftp.cup.hp.com/dist/networking/misc/listenq</a>.</p>

    <p>If folks are running Apache on a PA-8000 based system, they
    should consider "chatr'ing" the Apache executable to have a
    large page size. This would be "chatr +pi L &lt;BINARY&gt;."
    The GID of the running executable must have MLOCK privileges.
    Setprivgrp(1m) should be consulted for assigning MLOCK. The
    change can be validated by running Glance and examining the
    memory regions of the server(s) to make sure that they show a
    non-trivial fraction of the text segment being locked.</p>

    <p>If folks are running Apache on MP systems, they might
    consider writing a small program that uses mpctl() to bind
    processes to processors. A simple pid % numcpu algorithm is
    probably sufficient. This might even go into the source
    code.</p>

    <p>If folks are concerned about the number of FIN_WAIT_2
    connections, they can use nettune to shrink the value of
    tcp_keepstart. However, they should be careful there -
    certainly do not make it less than oh two to four minutes. If
    tcp_hash_size has been set well, it is probably OK to let the
    FIN_WAIT_2's take longer to timeout (perhaps even the default
    two hours) - they will not on average have a big impact on
    performance.</p>

    <p>There are other things that could go into the code base, but
    that might be left for another email. Feel free to drop me a
    message if you or others are interested.</p>

    <p>sincerely,</p>

    <p>rick jones<br />
     <a
    href="http://www.cup.hp.com/netperf/NetperfPage.html">http://www.cup.hp.com/netperf/NetperfPage.html</a>
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